The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Presently, some military aircraft, for example the EA-18G aircraft, carry a jamming pod that transmits a high power, electromagnetic (EM) wave jamming signal, that can occupy a relatively large bandwidth (Greater than 250 MHz). When communicating with the aircraft, the obvious solution is to use a frequency band outside the band where the jammer is operating. However, given tactical and interoperability considerations, it is sometimes necessary to be able to communicate using EM wave signals, with such an aircraft using the standard communications system carried onboard the aircraft, which may be operating in the frequency band where the jammer is transmitting a high power EM wave signal.
However, when a mobile platform equipped with electromagnetic wave jamming equipment is transmitting its jamming signal in the communications receive band, the interference-to-signal ratio is very large, and the communication signal may be drowned out by the jamming signal. Often, the jamming signal may be many orders of magnitude greater than the signal being received in the communications receiver.
There have been attempts at ameliorating the impact of an electromagnetic wave jamming signal for other narrow-band communications signals in other frequency bands. However, there is presently no suitable solution for a wide-band communications signal. The adaptive RF canceller of the present invention has a heritage in the field of acoustic noise canceling applications. However, there are two primary issues that must be dealt with in the wideband RF domain that are not issues in the acoustic domain. The bandwidth in the acoustic domain is typically about 20 kHz, while the RF domain is on the order of 250 MHz. The propagation velocity of sound is on the order of 330 meters/second compared to the speed of light at 3×108 meters/s. In the case of an acoustic noise canceller system, the signal travels through the electronics of the system much faster than the sound between the reference microphone and the speaker output. In the electromagnetic wave canceller scenario, the signal propagation time through the electronics is typically slower than from the coupler to the receive antenna, which therefore necessitates differences in the implementation of the canceller architecture.
Accordingly, there exists a need to overcome an electromagnetic wave jamming signal being emitted from a platform so that the jamming signal does not interfere with wireless communications to the platform.